Overview
The “Load jam protection” function protects the motor in case of sudden rotor locking or a jump in load increase. A quick motor shutdown avoids or reduces damage to drives, bearings, and other mechanic motor components. The rotor locking results in a jump in current increase in the phases. The current jump is used by the function as a recognition criterion.
For more detailed information on “Load jam protection” function, refer to SIPROTEC 5 devices, V8.30 & higher manuals.
To see other supported functions, click here.
Structure/Embedding of the Function
Setting Parameters
Setting parameters for Load jam protection
| Addr. | Parameter | C | Setting Options | Default Setting |
| Load-jam prot. | ||||
| _:1 | Load-jam prot.:Mode | off on test |
off | |
| _:2 | Load-jam prot.:Operate & flt.rec. blocked | no yes |
no | |
| _:101 | Load-jam prot.:Threshold for warning | 1 A @ 100 Irated | 0.030 A to 35.000 A | 1.500 A |
| 5 A @ 100 Irated | 0.15 A to 175.00 A | 7.50 A | ||
| 1 A @ 50 Irated | 0.030 A to 35.000 A | 1.500 A | ||
| 5 A @ 50 Irated | 0.15 A to 175.00 A | 7.50 A | ||
| 1 A @ 1.6 Irated | 0.001 A to 1.600 A | 1.500 A | ||
| 5 A @ 1.6 Irated | 0.005 A to 8.000 A | 7.500 A | ||
| _:103 | Load-jam prot.:Warning delay | 0.00 s to 600.00 s | 2.00 s | |
| _:102 | Load-jam prot.:Threshold for operate | 1 A @ 100 Irated | 0.030 A to 35.000 A | 2.000 A |
| 5 A @ 100 Irated | 0.15 A to 175.00 A | 10.00 A | ||
| 1 A @ 50 Irated | 0.030 A to 35.000 A | 2.000 A | ||
| 5 A @ 50 Irated | 0.15 A to 175.00 A | 10.00 A | ||
| 1 A @ 1.6 Irated | 0.001 A to 1.600 A | 2.000 A | ||
| 5 A @ 1.6 Irated | 0.005 A to 8.000 A | 10.000 A | ||
| _:6 | Load-jam prot.:Operate delay | 0.00 s to 600.00 s | 1.00 s | |
| _:105 | Load-jam prot.:Release delay | 0.00 s to 600.00 s | 5.00 s | |
Logic Diagrams & highlights
Typical Characteristic Curve of an Asynchronous Squirrel-Cage Motor
Example of the Time Characteristic Curve for Mechanical Rotor Locking
Logic Diagram of Load-Jam Protection
Example of a Complete Motor-Protection Characteristic Curve
